The present invention relates to tapping into conduits and more particularly, relates to hot tapping conduits.
For a variety of reasons, it is sometimes necessary to gain direct access to the contents of a pressurized or other fluid-conducting conduit. Two general methods exist to achieve this result. The first method is referred to as xe2x80x9ccold tappingxe2x80x9d. To xe2x80x9ccold tapxe2x80x9d a conduit, the conduit is de-pressurized and the contents usually removed. Cold tapping is usually considered the safest method of gaining direct access to the contents of a pressurized conduit since the contents are generally removed, thus, minimizing the likelihood of the contents coming in contact with a person.
Cold tapping does, however, have several drawbacks. For example, welders must often be called in to weld a tap onto the conduit or the conduit often cannot be de-pressurized for a variety or reasons such as the contents are needed for another processes or for environmental concerns. Furthermore, cold tapping a conduit is a time consuming process since the entire line, and not just a particular section thereof, may need to be drained and then treated. This can affect other processes, thus creating even more of a disturbance.
The second method of gaining direct access to the contents of a pressurized conduit is referred to as xe2x80x9chot tappingxe2x80x9d. Hot tapping is a term used to describe the situation where the access to the conduit is gained whilst the conduit is still under pressure or flow. A typical hot tap installation requires attaching a threaded coupling to the conduit at the desired location, usually through welding. Welding the coupling to the conduit often weakens the conduit and/or damages the contents of the conduit due to the extreme heat generated during the welding process.
Next, a temporary jig is attached to the conduit to drill through the coupling and then insert the tap (sensor, sampling probe, or other device). This is a lengthy process, requiring careful alignment, safety chains, and special tools and typically requires at least two people. Moreover, considerable space around the conduit is needed in order to allow the equipment and installers to have access to the conduit. The amount of space required could become a problem in areas with limited space such as ceilings and walls, or where other equipment is present. Furthermore, the drilling creates cuttings or xe2x80x9cchipsxe2x80x9d which can enter and contaminate the conduit or damage other devices located downstream.
Accordingly, what is needed is an apparatus or method of hot-tapping a conduit that minimizes or eliminates the hazards and difficulties typically associated with hot-tapping. The apparatus or method should reduce material and labor costs, as well as increase worker safety. The apparatus or method should also not require special tools such as drilling rigs, and work in areas with limited space considerations. Furthermore, the apparatus or method should minimize or eliminate the possibility of blowback of the contents that are under pressure.
The present invention features an apparatus for hot tapping a conduit. The apparatus includes a first cavity, a second cavity adapted to contain a sensor, a user activatable propellant adapted to be disposed in the first end of the first cavity, a plunger, and at least one passageway fluidly connecting the first and the second cavity when the plunger is disposed in the second position such that the propellant forces the sensor through the channel and into the conduit.
The plunger is disposed in the first cavity and includes a first end, a second end having a shearing surface, and an aperture disposed between the first and the second ends. In a first position, the plunger is disposed proximate the first end of the first cavity. When activated, the user activatable propellant forces the plunger from the first position to a second position proximate the second end of the first cavity such that the shearing surface of the plunger shears off a portion of the conduit creating an aperture in the conduit and retains the sheared portion of the conduit proximate the second end of the first cavity. In the second position, the aperture in the plunger is aligned with the second cavity and the aperture in the conduit to form a channel.
In one embodiment, the first passageway is proximate the first end of the plunger and the second passageway is disposed in the second cavity. When the apparatus is in first position, the first and the second passageways are not aligned. As a result, when the user activates the propellant, the plunger is propelled from the first position to the second position. When the apparatus is in the second position, the first and the second passageways become aligned and form a continuous passageway that fluidly connects the first and the second cavities. The propellant then flows through the first and the second passageways into the second cavity where the propellant forces the sensor through the channel. and into the contents of the conduit.
In another embodiment, the first passageway is disposed within the first cavity and the second passageway is disposed within the second cavity. When the apparatus is in the first position, the plunger blocks the first passageway so that the propellant cannot enter. Thus, when the user activates the propellant, the plunger is forced from the first position to the second position. When the plunger is in the second position, the first passageway is unsealed and the first cavity is in fluid communication with the second cavity. The propellant then flows into the second cavity and forces the sensor through the channel and into the contents of the conduit.
Optionally, the apparatus may include three or more cavities wherein the additional cavities are substantially the same as the second cavity. The plunger may also include a seal, such as an o-ring seal, between the plunger and the first cavity. A locking device and an anti-rotation device, such as a locking ring and groove and a channel respectively, is preferably provided that fixes the location of the sensor and/or the plunger within the conduit and/or first cavity.